<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
         .wrapper {
      min-width: 400px;
      max-width: 800px;
      display: flex;
      justify-content: flex-end;
    }

    .avatar {
      overflow: hidden;
      width: 48px;
      height: 48px;
      margin-right: 20px;
      border-radius: 50%;
      background: url(./images/avatar.jpg) no-repeat center / cover;
    }

    .wrapper textarea {
      flex: 1;
      height: 30px;
      padding: 10px;
      border-color: transparent;
      outline: none;
      resize: none;
      background: #f5f5f5;
      border-radius: 4px;
      transition: all 0.5s;
    }

    .wrapper textarea:focus {
      height: 50px;
      border-color: #e4e4e4;
      background: #fff;
    }

    .wrapper button {
      width: 70px;
      margin-left: 10px;
      border: none;
      color: #fff;
      background: #00aeec;
      border-radius: 4px;
      cursor: pointer;
    }

    .wrapper .total {
      margin-right: 80px;
      margin-top: 5px;
      color: #999;
      opacity: 0;
      transition: all 0.5s;
    }

    .list {
      display: flex;
      min-width: 400px;
      max-width: 800px;
    }

    .list .item {
      display: flex;
      width: 100%;
    }

    .list .item .info {
      flex: 1;
      border-bottom: 1px dashed #e4e4e4;
      padding-bottom: 10px;
    }

    .list .item p {
      margin: 0;
    }

    .list .item .name {
      color: #FB7299;
      font-size: 14px;
      font-weight: bold;
    }

    .list .item .text {
      padding: 10px 0;
      color: #333;
      font-size: 13px;

    }

    .list .item .time {
      color: #999;
      font-size: 12px;
    }
    </style>
</head>
<body>
    <div class="wrapper">
        <i class="avatar"></i>
        <textarea id="tx" placeholder="发一条友善的评论" rows="2" maxlength="200"></textarea>
        <button>发布</button>
      </div>
      <div class="wrapper">
        <span class="total">0/200字</span>
      </div>
      <div class="list">
        <div class="item" style="display: none;">
          <i class="avatar"></i>
          <div class="info">
            <p class="name">清风徐来</p>
            <p class="text">大家都辛苦啦，感谢各位大大的努力，能圆满完成真是太好了[笑哭][支持]</p>
            <p class="time">2099-10-10 20:29:21</p>
          </div>
        </div>
      </div> 
</body>
</html>
<script>
// 需求1. 文本域获取焦点 则让total 透明度改为1， 失去焦点的时候 透明度0
const txt = document.querySelector('#tx')
const total = document.querySelector('.total')

txt.addEventListener('focus', function () { 
total.style.opacity =1
 })

 txt.addEventListener('blur',function () {
    if(txt.value.length !== 0) return
    total.style.opacity =0
  })

// 需求2. 得到用户数的字符长度， 写到total盒子里面
// txt.addEventListener('keyup',function () {
//     // 模板字符串拼接长度length
//     total.innerHTML=`${txt.value.length}/200字`
//   })
// imput 顺畅一些
txt.addEventListener('input',function () {
    // 模板字符串拼接长度length
    total.innerHTML=`${txt.value.length}/200字`
  })

</script>